Automatic and electric fire alarm



Aug. 27, 1935. P. D] BELLA AUTOMATIC AND ELECTRIC FIRE ALARM Filed Oct. 3, 1934 2 Sheets-Sheet 2 Inventor P/uzl/ z'z-fiezzw Patented Aug. 27, 1935 PATENT OFFICE ssi'romnc am manic ms sums Thin]! Bi Bell, Philadelphia, Pa.

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invention relatestoautomltie-dectric 'iirealarmaandanobiectottheinventionisto provide improved electrically operated means for soundinganalarmwhenthetanperatureota room rises beyond a predetermined Mm The invention also consists in the provision of an improved type of thermal switch forming a partof thealarmdevice andadaptedto be arranged in circuit with a signal element, such as an audible signal, for example a. hell or the like tot automatically closing the circuit to the 818- nal'iathe event of tire.

invention together with its objects and advantages will be best understood 1mm a study ofthe icilowing description taken in connection with the accompanying drawings wherein:

,Figure 1 is a view illustrating diagrammatically the application of the invention.

Figure 2 is a plan view of the switch mocha- Figure3isaviewsimilartoFigure2 withthe cover of the switch casing removed.

Figure 4 is a longitudinal sectional view taken substantially on the line 4-4 of Figure 2, and

Figure 5 is a perspective view of a fusible element.

Referring to the drawings it will be seen that in accordance with the present invention there may be provided throughout a building one or more electrically operable audible signal devices, for example an electric bell Ill. Also properly located throughout the building will be one or more thermal switches indicated generally by the reference numeral II and arranged in circuit with the signal devices l0 and a transformer l2 in a manner, upon closing of a switch II to complete the circuit to the bell It to set the latter in operation for giving a warning as to the presence of tire.

Each of the thermal switches ll comprises a casing it which may be of any suitable material and which in the present instance is shown as being oblong and provided at the ends thereof with apertured flanges ll whereby through the medium of fastening devices such as screws orthelikethecasingmaybemountedtoa suitable support, as for example a wall, ceiling or the like. The casing I3 is also provided with a hinged lid hinged at one end to the casing as at It and provided at a relatively opposite end with a spring latch H for releasably holding the lid in closed position. 'Ihe handle II is also provided for the lid to facilitate opening and closing of the casing. For ventilation purposes the lid I! is provided with an opening is while Wm 00m 3, 1936, Still No. 746,7

3 Chime. (Cl. 200-142) oppmed Ialkof the casing 13 are prevailed-with openings 20.

Smtahly secured within the casing t3 adlaoent one end timreot are spaced partitions or supportmemoers 2| and 2: respectively. Tin partitron members 2|, :2 are formed of any suimbb material and secured to opposite sides In th partition =21 are pieces 23 of insulating material, one of which pieces is provided with circular extensions that flt in apertures provided in the partition 2| to accommodate terminal screws 2!. 34' to which are secured the circuit wires I. One of the binding screws serves as aflmfl contact while secured to the other of the h'hding screws, 24' is a spring contactmember '2.

Provided in the mrtition 22 is a guide sleeve 21 in which is slidable an operating planar 2. adapted to be projected for engaging the s zing contact 26 with the first mentioned term screw 34 in completing the circuit to the'boll 60. For projecting the plunger 28 there is provided a suitably constructed trigger 29 provided with spaced ears apertured to receive a pivot bolt 30 through the medium of which the trigger is pivotally mounted within the casing. Normally urging the trigger 29 to rotate in a clockwise direction for projecting the plunger 28 is a coil spring one end of which is engaged with a hook 3| secured to the lower end of the trigger 29 while the other end of the spring is anchored toanendwallofthecasingasshowninFlgure 4.

The thermal switch includes a thermal element indicated generally by the reference 1111-.

and has the ends thereof projecting outwardly of the casing through the openings 20 in the sides of the casing. Secured to the underside of the strip 33 is a second strip 34 of celluloid the ends of which are apertured as at 35 to accommodate hooks 36, 31 respectively provided on one end wall of the casing l3 and the free end of the trigger 29 as shown in Figure 4. Obviously with the thermal strip 34 thus engaged with the hook 36, 31 the trigger 29 will be held in the position shown in Figure 4 and out of engagement with the plunger 28, against the action of a coil spring 30, Also the ends of the strip 33 projecting outwardly of the casing will be contacted by the flame before the flames are in close proximity to the casing with the result that the thermal element will be destroyed quicker by the flames than merely by the melting thereof, and consequently the switch set in operation to close the circuit to the alarm device at the earliest possible moment.

As is obvious normally through the medium of the strip 34 engaged with the hooks 36, 31 in the manner shown in Figure 4 the switch contacts 24 and 26 are disengaged for interrupting the circuit to the alarm device In. When however the thermal element is burned or melted releasing the trigger 29, the latter under action of the spring 30 will rotate in a clockwise direction in a manner to engage the plunger 28 and force the same toward the right in Figure 4 to move the spring contact 26 into engagement with the contact 24 thus completing the circuit to the alarm l0, thereby setting the latter in operation.

It will be apparent that the element 32 may be easily replaced and the part reset to the position shown in Figure 4 after the fire has been extinguished thus leaving the switch II and the system in condition for subsequent operation.

Having thusdescribed my invention, what I claim as new is: f

1. In an automatic fire alarm the combination of afixed and a spring contact cooperable to close a circuit, a plunger for engaging the spring contact with the fixed contact, guide means for the plunger, a pivotally mounted trigger adapted to move into engagement with the plunger for shifting .the latter to thereby engage said contacts, spring means engaged with the trigger normally tion to the spring to thereby normally maintain the contacts disengaged.

2. Av switch of the character described comspring contact being arranged to engage the fixed contactfor completing a circuit, a plunger slidably mounted in the casing to engage the spring contact with the fixed contact, a trigger pivotally mounted in the casing, and adapted upon rotation in one direction to engage the plunger and force the latter into engagement with the spring contact to flex the spring contact into engagement with the fixed contact, a fusible element including a part arranged wholly within the casing, means on an end wall of the casing and the trigger connecting said part of the fusible element with said wall of the casing and trigger for normally retaining the same out of engagement with the plunger, and said fusible element having a second part the opposite ends of which project outwardly-of the casing through openings in the side walls of the casing.

3. In a device of the character described, a casing, a fixed contact and a spring contact mounted in the casing and insulated therefrom,

' said spring contact being normally spaced from the fixed contact, and cooperable with the fixed contact to complete a circuit, a plunger, guide and supporting means for the plunger and said spring contact having one end normally engaging one end of the plunger, a member pivotally mounted in the casing and adapted to rotate in one direction to engage the free end of the plunger for shifting the same to engage the spring contact with the fixed contact, spring means anchored to a wall of the casing and connected with said pivoted member for urging said pivoted member to rotate in said one direction, a fusible element extending transversely through said casing, and means on said pivoted member and a wall of the casing respectively for supporting said fusible member, and in a manner to utilize said fusible member as a means for normally retaining said pivoted member against rotating in said one direction.

PHILIP DI BELLA. 

